JPH01213493A - Double screen type papermaking apparatus - Google Patents

Abstract

PURPOSE: To provide the subject machine intended to obtain strip-shaped paper further improved in opacity and both sides uniformity by designing in a specifically curved fashion the interval through which a pair of endless belts travel vertically upward while nipping a paper. CONSTITUTION: This paper making machine has such a scheme that, a pair of screen-like endless belts 1, 2 are put to mutual contact on the surface of a forming cylinder 4, raised to a dehydrating roll 7 thereabove and then separated from each other on the surface of the dehydrating roll 7; a point where both the endless belts 1, 2 are joined together on the surface of the forming cylinder 4 is then fed with paper stock for paper making operation; there is provided a screen with a curved surface 5 inside the loop of the outside belt 2 on the downstream side of the forming cylinder 4; a 2nd curved surface (inner surface) 6 is provided downstream of the curved surface 5, and the center of curvature of the 2nd curved surface 6 is set opposite to that of the curved surface 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] <Industrial Field of Application> The present invention relates to a paper making device also called a twin wire former or the like, and particularly to the structure of a wet section in such a paper making device. One such papermaking apparatus is shown in FIG. 4 of the 1979 edition of rZerstoff' und Papler J, Volume 4, Page 176.

<Prior Art> This type of paper making apparatus has already been proven to be highly reliable and is capable of producing high quality paper strips with good opacity and slight difference between the front and back sides. However, it is desirable to further improve such performance.

<Problems to be Solved by the Invention> In view of the above, the main object of the present invention is to provide a double screen paper manufacturing apparatus for producing high quality paper strips, especially in terms of opacity and uniformity on the front and back sides. It is about providing.

[Structure of the Invention] <Means for Solving the Problems> An object of the present invention as described above is to provide a screen forming a pair of endless belts having a common section that is conveyed generally upward, and a belt between the two screens. a material supply port for supplying the fibrous material to the common section; a first curved surface that is in the common section and comes into contact with one inner surface of the screen; and a dewatering roll provided at the end of the common section. (a) a forming cylinder located near the monthly charge supply port provided at the starting end of the common section and inside the other loop of the screen; b) a second curved surface that abuts the other inner surface of the screen, and (c) centers of curvature of the first and second curved surfaces are located on opposite sides of the common section. , (d) the second curved surface is located downstream of the first curved surface when viewed in the conveyance direction of both screens, and (e) the second curved surface is located downstream of the first curved surface. This is achieved by providing a paper making device characterized by a shorter curved surface than the curved surface of the paper machine.

Effect> In this way, both screens come into sliding contact with alternating curved surfaces along the conveyance path. A forming cylinder with a perforated shell is arranged downstream of the material feed opening, by means of which the direction of conveyance of the two screens is deflected.

The screen conveyed along the common section slides against a curved surface that is adjustable in the direction of approach and separation, and is deflected in a different direction by the curved surface. The screen then slides against a second curved surface, which is considerably shorter than the first curved surface, and is deflected back to its original direction. A dewatering roll is provided at the end of the common section of the screens, and the conveying direction of both screens is changed by this dewatering roll.

According to the prior art, dewatering was carried out only by means of a shaped cylinder and a single curved surface. Even if the dewatering surface is extended beyond a predetermined length, the dewatering ability will not be improved. Based on the invention, by using a second curved surface, a significant improvement in the dewatering capacity is achieved, and at the same time a significant improvement in the opacity and front-to-back uniformity of the paper produced is achieved. be done.

<Embodiments> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The inner screen 1 and the outer screen 2 are each configured as an endless belt. These screens 1
．． 2 are conveyed along a predetermined common route in a certain part. This common path runs from bottom to top along a substantially vertical direction.

However, this common path may be tilted within an angular range of up to about 30 degrees. The upstream end of this common pathway is
A wedge-shaped inlet gap 3 is defined.

In this part, both screens 1.2 are connected to the forming cylinder 4.
is wound around. On the downstream side of the forming cylinder 4, inside the loop of the outer screen 2, a screen table is provided. This screen table has a curved surface 5. This curved surface 5 may be formed by combining a plurality of planes, is provided along the conveyance direction of both screens, and is in sliding contact with the inner surface of the outer screen 2. This curved surface 5 has a curved shape such that its center of curvature is located on the right side in FIG. 1 of the perpendicular common path of both screens 1.2.

A second curved surface (inner surface) 6 is provided downstream of the first curved surface (outer surface) 5 . The second curved surface 6 is curved so that its center of curvature is located on the left side of both screens 1 and 2 in FIG. This second curved surface 6
consists in this example of a single beam member extending over the entire width of both screens 1.2. The beam member is tiltable so that the force with which the curved surface 6 is pressed against the screens 1.2 can be adjusted. In this way, water can be dewatered from inside the loops of the outer screen 2 in a perpendicular direction. Dewatering of the other side takes place from inside the loops of the inner screen 1 in the area connecting this area.

A screen dewatering roll 7 is provided at the end of the common conveyance path of both screens 1.2.

This dewatering roll 7 has a perforated skin and at the top of this screen dewatering roll 7 the two screens 1.2 separate from each other.

The material supply device 8 is arranged to supply material to the artificial cavity 3 over the entire width of the papermaking device.

The fibrous material is transported along the transport path of both screens 1.2 as described above, during which the necessary dewatering takes place. The strip-shaped fibrous material sent out from the terminal end of the dewatering roll 7 is conveyed toward the subsequent press while being adhered to the outer screen 2.

Compared to the first curved surface 5, the second curved surface 6 is provided over a very small length along the conveying direction of the screen, and for example, the length of the first curved surface 5 is When the length is 1.4 m, the length of the second curved surface is, for example, 5 m.
cm.

The first curved surface in this embodiment is completely closed and impermeable to water. The second curved surface 6 is also generally closed and has a similar structure to the first curved surface 5 in other respects, for example, it may be a combination of a plurality of planes or foils.

[Brief explanation of the drawing]

FIG. 1 is a simplified side view showing the structure of a paper making apparatus according to the present invention. 1.2...Screen 3...Inlet gap 4...Forming cylinder 5.6...Curved surface 7...Screen dewatering roll 8...Material supply device patent Applicant Yotsuto M. Voith GmbH

Claims (3)

[Claims] (1) A screen forming a pair of endless belts having a common section that is conveyed generally upward, a material supply port for supplying the fibrous material between the two screens, and a material supply port that is located in the common section. A double-screen papermaking apparatus comprising: a first curved surface that abuts one inner surface of the screen; and a dewatering roll provided at the end of the common section, the apparatus comprising: (a) a starting end of the common section; (b) a second molding cylinder located in the vicinity of the material supply port provided in the part and inside the other loop of the screen; (b) a second molding cylinder in contact with the other inner surface of the screen;
(c) the centers of curvature of the first and second curved surfaces are located on opposite sides of the common section, and (d) the second curved surface has A paper making apparatus, characterized in that the second curved surface is located downstream of the first curved surface when viewed in the transport direction of the screen, and (e) the second curved surface is shorter than the first curved surface. (2) The length of the second curved surface is approximately 1/20 to 1/10 of the length of the first curved surface, according to claim 1. paper making equipment. (3) The second curved surface is formed on a beam member extending in the width direction of both the screens, and the beam member is adjustable in a direction toward and away from the both screens. Claim 1 characterized in that
The paper manufacturing apparatus according to item 1 or 2.